L'Hermitte's sign describes electrical buzzing sensations in the limbs and body brought on by movement of the neck. These sensations are known as paraesthesia and include tingling, buzzing, electrical shocks, partial numbness and sharp pains. L'Hermitte's is most often triggered by lowering the head so that the chin touches the chest. The sensations usually only last for a second or two. It has been called the "barber shop" symptom because it is often evoked when the hairdresser asks you to lower your head when he or she shaves the back of your neck.
L'Hermitte's is associated with a number of conditions including arthritis, cervical spondylosis, disc compression, pernicious anaemia, tumours and multiple sclerosis. In many cases, the cause cannot be found.
Because the cervical spinal cord is a frequent target for multiple sclerosis it is a very common symptom of MS. Aproximately two thirds of people with multiple sclerosis experience L'Hermitte's symptom at some point during the course of their disease.
In MS, L'Hermitte's is an indicator of lesions in the cervical spine (the part of spine in the neck). Movement of the neck causes the damaged nerves (the demyelinated neurons) to be stretched and send erroneous signals. The symptoms can occur anywhere below the neck and many people with MS find that it moves around their body from one day to the next.
Sensory symptoms of multiple sclerosis